The baroreceptors send afferent signals via which nerves?

• A. Optic nerve II for carotid sinus; facial nerve VII for aortic arch.
• B. Glossopharyngeal nerve IX for carotid sinus; vagus X for aortic arch.
• C. Trigeminal nerve V for carotid sinus; hypoglossal XII for aortic arch.
• D. All baroreceptor signals travel via vagus X.

Answer: (B)

Baroreceptors sense blood pressure and send signals to the brainstem through specific cranial nerves. The carotid sinus afferents travel via the glossopharyngeal nerve (IX), often called the carotid sinus or Hering’s nerve, to reach the nucleus tractus solitarius. The aortic arch afferents travel via the vagus nerve (X) to the same brainstem center. This is why the correct pairing is IX for the carotid sinus and X for the aortic arch. Other nerves listed aren’t involved in conveying baroreceptor signals—the optic nerve handles vision, the facial and trigeminal nerves aren’t the primary pathways for this reflex, and the hypoglossal nerve serves tongue motor function. Also, not all baroreceptor signals travel via the vagus; only the aortic arch afferents do, while carotid sinus afferents use IX.